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Category: Error Handling

MRAppMaster Errors Running MapReduce Jobs

I have a post looking at potential causes when PolyBase MapReduce jobs are unable to find the MRAppMaster class:

Let me tell you about one of my least favorite things I like to see in PolyBase:

Error: Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster

This error is not limited to PolyBase but is instead an issue when trying to run MapReduce jobs in Hadoop. There are several potential causes, so let’s cover each of them as they relate to PolyBase and hopefully one of these solves your issue.

Click through for four potential solutions to what ails you.

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String or Binary Data and Associated Bug

Brent Ozar looks at the “String or binary data would be truncated” improvement:

Don’t leave this trace flag enabled.
There’s at least one bug with it as of today on SQL Server 2017 CU13: table variables will throw errors saying their contents are being truncated even when no data is going into them. Andrew Pruski reports:

Special shout out to three of my co-workers on finding that issue. I had nothing to do with it but will take credit nonetheless.

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Handling Errors in Kafka Connect

Robin Moffatt shows us some techniques for handling errors in your Kafka topics:

We’ve seen how setting errors.tolerance = all will enable Kafka Connect to just ignore bad messages. When it does, by default it won’t log the fact that messages are being dropped. If you do set errors.tolerance = all, make sure you’ve carefully thought through if and how you want to know about message failures that do occur. In practice that means monitoring/alerting based on available metrics, and/or logging the message failures.

The most simplistic approach to determining if messages are being dropped is to tally the number of messages on the source topic with those written to the output:

Read on for a few different tactics and how you can implement them.

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Attempted To Read Or Write Protected Memory

Kenneth Fisher explains a nasty-looking error to us:

So, are you seeing this error?

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

If you read the error it might freak you out a bit. The key words memory and corrupt can be a bit .. concerning. Fortunately in this case they are also rather misleading.

Click through to understand what’s going on and how you can fix the problem if you see this error.

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SSIS Error “Deserializing The Package”

Andy Leonard troubleshoots an odd error in SSIS:

Exception deserializing the package “Operation is not valid due to the current state of the object.”. (Microsoft.DataTransformationServices.VsIntegration)

As a professional consultant who has been blogging about SSIS for 12 years and authored and co-authored a dozen books related to Microsoft data technologies, my first response was:
“Whut?!”

That is a reasonable first response. Fortunately, Andy also had a second response which was more helpful in finding the root cause.

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Could Not Clear Differential Bitmap

Jack Vamvas takes us through a reason why you might get error 3041:

An error message has started appearing in the SQL Server Error Logs during a nightly full backup.

Could not clear ‘DIFFERENTIAL’ bitmap in database ‘Database1’ because of error 9002. As a result, the differential or bulk-logged bitmap overstates the amount of change that will occur with the next differential or log backup. This discrepancy might slow down later differential or log backup operations and cause the backup sets to be larger than necessary. Typically, the cause of this error is insufficient resources. Investigate the failure and resolve the cause. If the error occurred on a data backup, consider taking a data backup to create a new base for future differential backups.

Click through for the root cause and solution.

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Common DAX Error Messages

Marco Russo takes us through some of the more common Power BI error messages around writing DAX:

The message should help the author fix the code, but sometimes the text suggests a possible action without describing the underlying issue. The goal of this article is to explain the more common DAX error messages by providing a more detailed explanation and by including links to additional material. If some terms are not clear, look at the linked articles or consider some free self-paced training such as Introducing DAX.

Click through for several examples.

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Bubbling Up HTTP Status Errors In Power Query

Tony McGovern takes us through a method involving Power Query + M of giving end users useful information when a web request fails:

So how does this relate to error tables? Like most well-documented APIs, the U.S. Census Bureau API has a page devoted to listing and describing all the possible response codes that can be returned by their service. I take this information and build an internal table within the query that defines and describes these response codes in my own words. I’m now able to throw custom messages that make the difference between a 400 response code and a 404 response code more obvious.

For example, in the code below, I use the Error.Record function to create individual records that allow me to catch these unsuccessful requests and throw my own custom error messages to the user. I then create an extra field in each record called ‘Status’, which maps each HTTP response code returned by the API to a corresponding error message of my choosing:

There’s a bit of work, but the end result is a fairly simple explanation for end users.

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Capturing SQLCMD Errors

Jack Vamvas shows us how we can capture errors from SQLCMD:

I’m executing  code using SQLCMD from a batch file . The code points to a sql file and there is also an output file. 


SQLCMD -E -S MYSERVER\INST1 -i “setup_job_entry.sql” -o “setup_job_entry.log”


But I noticed that if the actual SQLCMD returns an error , for example , if I’m connecting to  an server which doesn’t exist this error message will appear in the output file – but there will  not be an ERROR number , which would allow me to trap and return an appropriate message 

There is a way and Jack shows us how.

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Tracking Errors In Power BI

Reza Rad has a lengthy post covering how you can track errors in Power Query:

To build a robust BI system, you need to cater for errors and handle errors carefully. If you build a reporting solution that the refresh of that fails everytime an error occurs, it is not a robust system. Errors can happen by many reasons, In this post, I’ll show you a way to catch potential errors in Power Query and how to build an exception report page to visualize the error rows for further investigation. The method that you learn here, will save your model from failing at the time of refresh. Means you get the dataset updated, and you can catch any rows caused the error in an exception report page. To learn more about Power BI, read Power BI book from Rookie to Rock Star.

There’s a lot of work, but also a lot of value in doing that work.

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